Interpersonal influences in human visual attention: from behaviour to EEG.

Abstract

Human evolution has shaped us into social animals, who are continually immersed in social interactions, constantly performing tasks with others and sharing our reality with them (Dunbar, 2003; Tomasello, Carpenter, Call, Behne, & Moll, 2005). For many of these interactions to be successful, it is necessary to pay attention to the same spatial locations with other individuals. Surprisingly however, this specific low-level aspect of our social life (i.e., attending to the same spatial locations with others) is not well understood. The present PhD work aims at contributing to this understanding by investigating whether paying attention towards the same spatial location with another person modulates one’s attention performance, along with its social, cognitive, and neural implications. In this line, the classic visuospatial sustained attention paradigm (e.g., Eimer, 1996; Mangun & Hillyard, 1988; Mangun & Buck, 1998) was adapted so it could be independently performed by two people (a dyad) sitting next to each other, to examine how visual attention performance (reaction times, RTs) is interpersonally modulated when an experiment partner is paying attention to the same or a different spatial location (aka., dual attention paradigm). In this paradigm (Experiment 1), participants performed a visual go/no-go task, responding to visual targets while attending to the same vs. different spatial location than the experiment partner. A typical attention effect was present in RTs (i.e., faster responses to targets appearing at the attended locations compared with those at the unattended locations) when the dyad attended to different locations. This attention effect, however, was significantly reduced when the participants shared the attentional locus (aka., dual attention effect). This pattern was reversed when single participants performed the task in isolation (Experiment 2), suggesting that the reduction in the attention benefit was socially driven between individuals (interpersonally). Additional experiments showed that the dual attention effect persisted under an increased perceptual load (Experiment 3), was not modulated by the group membership status attributed to the task partner (i.e., social closeness; Experiment 4), and disappeared once the partner was performing the task from a separate room (i.e., physical closeness; Experiment 5). Finally, an electroencephalography (EEG) study (Experiment 6) investigated the neural underpinnings of the dual attention effect, focusing on the information processing stage(s) influenced by dual attention. The aim was to understand whether the dual attention effect took place at a sensory level vs. a cognitive control stage. Event-related potentials (ERPs) and neural oscillations suggested that the effect was driven by a cognitive control process, and also showed an enhancement in the early sensory level information processing in the brain. Both the N2b ERP component and mid-frontal theta oscillations pointed towards a stronger need for control when sharing the attentional locus with another person in the dual attention task, while the P1 component yielded an enhancement in the attention effect in the attention sharing condition. The P1 effect may be top-down driven through alpha band long-range communication from prefrontal to posterior areas. Likely higher order processing related accounts were proposed for the current findings (e.g., linked to response inhibition, or mentalising/monitoring others). The current thesis made the first attempt to place dual attention as a bridge between the general shared attention perspective (Stheynberg 2015) and the overt behavioural interplay characterising joint attention and joint action. In addition, the present results could have ubiquitous real-life implications, and may give us some clues about how to optimize daily performance in dual-attention- like environments (e.g., classrooms/working spaces).